The present apparatus relates, generally, to an air filter system used in air conditioning systems.
In recent years, there has been a growing interest to improve the indoor air quality in homes and commercial buildings. One of the simplest ways to provide a certain level of improvement is through filtering the air circulated by conventional heating and air conditioning systems. The conventional heating and air conditioning system typically filters the intake air drawn into the system. Typically, the intake air duct is referred to as the return air duct. The intake is usually located on a wall or ceiling and covered by a grill or louver. The grill or louver cover usually fits in a frame, mounted in the wall or ceiling, which opens into the return air duct. Typically, the grill or louver cover is almost flush with the wall or ceiling to create an aesthetically pleasing appearance. In the conventional heating and air conditioning system, a filter will be set within the frame just behind the grill cover and held in place by the cover. However, to improve or maintain the air quality, the filter must remain clean. Thus, the filter requires periodic cleaning or replacement.
Presently, conventional return air filter systems utilize a filter that is approximately 1xe2x80x3 in thickness. These filters vary in length and width depending on the size of the return air duct and the frame which opens into the room. The typical return air duct opening consists of wall or ceiling mounted frame that is configured to accept the 1xe2x80x3 thick filter. Typically, the filter is held in place by a cover grill that fits in the wall or ceiling mounted apparatus. The cover grill can be hinged and is usually held closed by some type of fastener. The typical filter is readily available in a variety of lengths and widths.
One of the primary drawbacks of the 1xe2x80x3 thick filter is that it requires cleaning and/or replacement often in less than one month of service. Although there are a variety of filter materials and filter element configurations available which may help increase the life of the filter by allowing relatively easy cleaning or prolonging the time between cleaning or replacing, the 1xe2x80x3 thick filters are still limited in filtering efficiency. Thus, the requirement of frequent cleaning or replacement becomes an inconvenient chore resulting in the filters being used longer than recommended. This problem is even more compounded if, for instance, the return air opening is not easily accessible. The opening could be in a ceiling which cannot be reached without a ladder and thus in accessible to persons with age or physical limitations. The opening could also be placed in a small and confined space again limiting its access.
To overcome these disadvantages, a variety of devices have come about in this very crowded prior art field. The devices have ranged from installing filter containing frames on air intake grills as well as the outlet air grills. U.S. Pat. No. 6,361,578 discloses a filter within a frame that is attached onto the existing grill of an air vent issuing air into the room. Likewise, U.S. Pat. No. 5,947,815 discloses a filter within a frame that is attached to the outside of an existing grill of an air vent. The ""578 patent discloses attachment by magnetic backing and the ""815 patent discloses attachment to the grill by mounting brackets. Prior art, such as U.S. Pat. Nos. 5,863,310 and 6,030,427 disclose installing new frames into the wall or ceiling at the return air duct opening, thus, requiring the removal of any existing grill and framework. The prior art discloses a variety of easy to open grill covers (""578 patent), hinged covers (""310 patent and ""427 patent) and even snap on covers (U.S. Pat. No. 4,334,899). Some of these devices are not flush with the wall or ceiling and thus could create other problems while other devices are flush mounted but included cumbersome installation. A common element of the prior art devices is that they include this filters which are usually 1xe2x80x3 or less in thickness. However, no matter how easy the filter replacement becomes, the major disadvantage is still the thickness of the filter and its normally short efficient life of as little as one month.
One solution to this problem is the use of a thicker filter which would be much more efficient and would require less frequent cleaning or replacement. Currently, there are thicker filters available for return air systems. However, the conventional air return system is configured to only accept the 1xe2x80x3 thick filter. Also, most of the prior art devices use a filter approximately 1xe2x80x3 thick.
It is thus a desire to have an apparatus that can adapt the conventional air return system to accept a thicker filter. This desired apparatus should be easy to install and require a minimum amount of hardware. Preferably, this apparatus would fit inside the existing air duct wall or ceiling opening, require no modification of the existing frame, and utilize the existing grill cover without modification. Thus this apparatus should consist of a frame that can fit inside the existing return air duct frame into which the current 1xe2x80x3 thick filter fits. This apparatus should be attached to the existing return air duct frame with sheet metal screws or other fasteners and be free from air leakage which would bypass the filter. This apparatus should further be able to accommodate the existing thicker air filters which are readily available and are approximately 4xe2x80x3 thick. This thicker filter would be capable of efficient filtering for as long as one year at a time before requiring cleaning or replacement.